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  1. #21
    Sirius Glass's Avatar
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    Quote Originally Posted by Nicholas Lindan View Post
    Wellllll, most timers only use one relay inside -- the NC contacts go the to safelight outlet and the NO contacts go to the enlarger.
    Well, there is another solution: daisy chain the timers [use the first timer switched outlet into which plug the next timer] with the safelights using the last outlet in the series. That way any timer in use will turn off the safelights! Now the requirement has been met without opening any boxes or touching a soldering iron!

    Or to quote a poster sold at www.despair.com =>
    "None of Us is Dumb as All of Us."
    ##### http://www.despair.com/meetings.html #####

    Steve
    Last edited by Sirius Glass; 05-16-2010 at 12:15 PM. Click to view previous post history. Reason: If your gonna' quote some, at least get it right! <<Snark, Snark>>
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  2. #22
    Steve Smith's Avatar
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    That's far too simple and elegant!


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  3. #23
    Sirius Glass's Avatar
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    Quote Originally Posted by Steve Smith View Post
    Quote Originally Posted by Sirius Glass View Post
    Well, there is another solution: daisy chain the timers [use the first timer switched outlet into which plug the next timer] with the safelights using the last outlet in the series. That way any timer in use will turn off the safelights! Now the requirement has been met without opening any boxes or touching a soldering iron!

    Or to quote a poster sold at www.despair.com =>
    "None of Us is Dumb as All of Us."
    ##### http://www.despair.com/meetings.html #####

    Steve
    That's far too simple and elegant!


    Steve.
    And it is free, so there is no relief for GAS. :o

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  4. #24
    clayne's Avatar
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    Trigger the same set of safelights from independent timers?

    Need to use the timers concurrently.
    Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.

    http://www.flickr.com/kediwah

  5. #25
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    You need to use a relay for each timer and run the coils separately via each timer and the contacts (normally open) in series on the safelight power line. The safelight is plugged into it's own wall outlet and the safelight outlets on the timers power the relay coils. All power circuits are separate from each other and no chance of a short circuit.
    Gary Beasley

  6. #26
    Sirius Glass's Avatar
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    Quote Originally Posted by glbeas View Post
    You need to use a relay for each timer and run the coils separately via each timer and the contacts (normally open) in series on the safelight power line. The safelight is plugged into it's own wall outlet and the safelight outlets on the timers power the relay coils. All power circuits are separate from each other and no chance of a short circuit.
    I am not sure that is quite right. Could you explain in more detail so i [we] could be sure we understood correctly?

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  7. #27
    glbeas's Avatar
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    Each timer has an outlet that energises for the safelight. Use this to energise the coil of a relay for each timer. The contacts should be wired to an outlet daisy chain style (in series) so both have to be energised for the safelight to be on. The safelight plugs into this setup. I'd put the relays in a project box with clearly marked cords for the timer connections and a power cord for the safelight to plug in the wall and an outlet to plug the safelight in to. Heres a rough sketch. I could put together a working circuit in minutes if I had the parts on hand.
    It could easily be set up for a normally closed setup to actively turn off the circuit using the enlarger plug or with a normally open to use the safelight plug if available.
    Attached Thumbnails Attached Thumbnails schematic.jpg  
    Gary Beasley

  8. #28
    clayne's Avatar
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    Quote Originally Posted by glbeas View Post
    Each timer has an outlet that energises for the safelight. Use this to energise the coil of a relay for each timer. The contacts should be wired to an outlet daisy chain style (in series) so both have to be energised for the safelight to be on. The safelight plugs into this setup. I'd put the relays in a project box with clearly marked cords for the timer connections and a power cord for the safelight to plug in the wall and an outlet to plug the safelight in to. Heres a rough sketch. I could put together a working circuit in minutes if I had the parts on hand.
    It could easily be set up for a normally closed setup to actively turn off the circuit using the enlarger plug or with a normally open to use the safelight plug if available.
    Gary, similar to an earlier post with SPST relays as an example. Either way, your method also looks sound to me. I think the key factor here is the inline or serial use of relays to guarantee either timer will indirectly (via relay) create an open situation in the main circuit.

    I'll rig something up in the coming months and let you guys know if I blew anything up.

    BTW, given a typical US 120vac/15a circuit, I'd presume we wouldn't be drawing 15 amps through the control side of the relay, as that would be nuts. Is the solenoid (or similar) on the coil side of the relay the only limiting factor of current draw from it's source - or does it use some form of resistor?
    Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.

    http://www.flickr.com/kediwah

  9. #29
    Sirius Glass's Avatar
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    Quote Originally Posted by glbeas View Post
    Each timer has an outlet that energises for the safelight. Use this to energise the coil of a relay for each timer. The contacts should be wired to an outlet daisy chain style (in series) so both have to be energised for the safelight to be on. The safelight plugs into this setup. I'd put the relays in a project box with clearly marked cords for the timer connections and a power cord for the safelight to plug in the wall and an outlet to plug the safelight in to. Heres a rough sketch. I could put together a working circuit in minutes if I had the parts on hand.
    It could easily be set up for a normally closed setup to actively turn off the circuit using the enlarger plug or with a normally open to use the safelight plug if available.
    Thanks for your clarification.

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  10. #30
    Steve Smith's Avatar
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    Whilst this two really version will work fine, Nicholas Lindan's single relay version is simpler and Sirius Glass's no relay version is simpler still.

    Quote Originally Posted by clayne View Post
    BTW, given a typical US 120vac/15a circuit, I'd presume we wouldn't be drawing 15 amps through the control side of the relay
    Or through the contacts unless you're running 1800 watts of safe light.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

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